package com.youdianstar.app.common.util;

import android.util.Log;

import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;

import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;

/**
 * File: AESUtil
 * Author: 82149 Create: 2020/5/18 18:14
 * Changes (from 2020/5/18)
 * --------------------------------------------------
 * describe:
 * ---------------------------------------------------
 */
public class AESUtil {
    /**
     * key
     */
    private static final String KEY_ALGORITHM = "AES";
    /**
     * 默认的加密算法
     */
    private static final String DEFAULT_CIPHER_ALGORITHM = "AES/ECB/PKCS5Padding";

    /**
     * AES 加密操作
     *
     * @param content  待加密内容
     * @param password 加密密码
     * @return 返回Base64转码后的加密数据
     */
    public static String encrypt(String content, String password) {
        try {
            // 创建密码器
            Cipher cipher = Cipher.getInstance(DEFAULT_CIPHER_ALGORITHM);
            byte[] byteContent = content.getBytes("UTF-8");
            // 初始化为加密模式的密码器
            cipher.init(Cipher.ENCRYPT_MODE, getKey(password));
            // 加密
            byte[] result = cipher.doFinal(byteContent);
            //通过Base64转码返回
            return Base64Util.encode(result);
        } catch (Exception ex) {
            Log.e("encrypt: {}", ex.toString());
        }

        return null;
    }

    /**
     * AES 解密操作
     *
     * @param content
     * @param password
     * @return
     */
    public static String decrypt(String content, String password) {

        try {
            //实例化
            Cipher cipher = Cipher.getInstance(DEFAULT_CIPHER_ALGORITHM);

            //使用密钥初始化，设置为解密模式
            cipher.init(Cipher.DECRYPT_MODE, getKey(password));

            //执行操作
            byte[] result = cipher.doFinal(Base64Util.decode(content));
            String s = new String(result, "UTF-8");
            return s;
        } catch (Exception ex) {
            Log.e("decrypt: {}", ex.toString());
        }

        return null;
    }

    private static SecretKeySpec getKey(String password) {
        byte[] arrBTmp = password.getBytes();
        // 创建一个空的16位字节数组（默认值为0）
        byte[] arrB = new byte[16];
        for (int i = 0; i < arrBTmp.length && i < arrB.length; i++) {
            arrB[i] = arrBTmp[i];
        }
        SecretKeySpec skeySpec = new SecretKeySpec(arrB, "AES");

        return skeySpec;
    }

    /**
     * 生成加密秘钥
     *
     * @return
     */
    private static SecretKeySpec getSecretKey(String password) {
        // 返回生成指定算法密钥生成器的KeyGenerator对象
        KeyGenerator kg = null;
        try {
            kg = KeyGenerator.getInstance(KEY_ALGORITHM);
            SecureRandom random = SecureRandom.getInstance("SHA1PRNG");
            random.setSeed(password.getBytes());
            //AES 要求密钥长度为 128
            kg.init(128, random);
            //生成一个密钥
            SecretKey secretKey = kg.generateKey();
            // 转换为AES专用密钥
            return new SecretKeySpec(secretKey.getEncoded(), KEY_ALGORITHM);
        } catch (NoSuchAlgorithmException ex) {
            Log.e("getSecretKey: {}", ex.toString());
        }
        return null;
    }
}
